The present invention generally relates to light emitting diodes (LEDs) and in particular to LEDs that are coated with one or more phosphor materials.
An LED is a semiconductor-based light source. LEDs are used as indicator lamps in many devices and are increasingly used for general lighting. When an LED is activated, electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor. LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.
In some applications, a phosphor material is disposed on top of the LED and used to convert monochromatic light from a blue or ultra-violet LED to broad-spectrum white light, much in the same way a fluorescent light bulb works. This method involves coating LEDs with a mixture of phosphors of different colors to form the desired color of white light. Depending on the color of the original LED, the mixture of phosphors of different colors and the amount of phosphors can be varied to achieve the desired white light color.